Rotary impact, ratchet-type wrench



April 21, 1959 R POTTER 2,882,772

ROTARY IMPACT. RATCHET-TYPE WRENCH Filed May 27, 1957 33 I I 2a 5 55 If 3 f6 4 k YF- 29 L United States Patent ROTARY-IMPACT, RATCHET-TYPE WRENCH Richard Plews Potter, Kew, Victoria, Australia, assignor to Maurice Ravdell, Misha Ravdell, and Leonard Maurice Stanton, all of Melbourne, Victoria, Austraha Application May 27, 1957, Serial No. 661,687

5 Claims. (Cl. 81-52.3)

This invention relates to shock wrenches for the loosening and complete removal of nuts, studs or bolts which through adhesion caused by corrosion, damaged threads, expansion and contraction due to temperature changes, overtightem'ng, or chemical action cannot be removed by ordinary spanners or wrenches operating on manually applied leverage principles.

It is customary in practice to loosen or endeavour to loosen an overtight or firmly adhering nut, by striking a spanner applied to the nut or by the use of a punch or the like applied to the corners of the nut and struck with a hammer. factory in that the spanner or the nut or both are apt to be damaged.

Now the principal object of this invention is to provide a simple, efiicient and durable device which is convenient and easy to use, very effective for loosening an overtight or adhering nut or the like, and can be manufactured at relatively low cost.

A further object is the provision of a device of the type referred to, which, after it has been used to break the adhesion between a screw-threaded member and an overtight or firmly adhering nut, may then be used more or less in the manner of a known type of ratchet wrench to complete the unscrewing of the nut from the threaded member.

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accommodate part of the cylindrical central portion 17 and a square-sectioned end portion 18 of a socket spanner adapter indicated generally by the reference 19. The cylindrical inner portions 15, 16 are of such a size as to neatly accommodate the reduced end portion of a stabilizing bar 20 which is inserted into the openings in one end of the impact shaft during use of the device. The outer end of the stabilizing bar 20 is fitted with a curved holding plate 21 to enable the operator to exert a force along the axis of the impact shaft to enable the operator to hold the tool in position during use.

The impact shaft is rotatably mounted within a hollow cast steel housing 22 having a removable end plate 23 which is bolted in place after theinsertion of the impact shaft into the housing. The latter also carries an elongated hollow boss 24 to which a long handle 25 is rigidly projections comprising radially sloping shoulders 28 dis- Such methods even if efiective are not satisposed at 90 intervals around the shaft, and connected by gently sloping curved surfaces 29, the projections being formed integrally with or rigidly connected to the shaft. The projections are disposed within the housing 22 which is shaped tofit neatly around them while allowing rotation of the shaft and projections in the housing. Disposed within the elongated hollow boss 24 is a pawl 30 which is urged radially towards the centre of the impact shaft by a compression spring 31 so that it normally rides on one of the curved surfaces 29. The pawl 30 is provided Another object is to provide a device of the type referred to, which can be used for the loosening or tightening of nuts or the like of all normal sizes and with nuts or the like having either a right or left hand thread.

Although the novel features which are believed to be characteristic of this invention will be more particularly has been set forth for purposes of illustration. In these drawings:

Figure l is an exploded perspective view of one form of shock wrench in accordance with the invention;

Figure 2 is a sectional view on an enlarged scale through a portion of the device shown in Figure 1;

Figure 3 is a sectional view taken on the line 3-3 in Figure 2;

Figure 4 is a perspective view of a part of the device and Figure 5 is a side elevation of a portion of a modified form of device according to the invention, parts thereof being broken away.

As shown in Figures 1 to 4 of the drawings, the shock wrench is provided with an impact shaft 10 which is hollowed at both ends. The openings in the ends of the shaft comprise cylindrical outer portions 11, 12, square sectioned central portions 13, 14 and cylindrical inner portions 15, 16. The outer cylindrical portions 11, 12. and the central portions 13, 14 are of such a size as to neatly one one side with a flat vertical face 32 (as seen in Figure 2) which is adapted to engage and co-act with the shoulders 28 as hereinafter described, while the base of the opposite side of the pawl is sloped as at 33 (Figure 3) for a purpose referred to hereinafter.

The adapter 19, besides having a cylindrical portion 17 and a square-sectioned portion 18 at one end as previously described, also has a square-sectioned portion 38 at its other end which is adapted to fit into any of the head pieces 34 of a standard socket spanner.

In use of the device, say to unscrew a nut which cannot be moved by means of normal hand operated spanners or wrenches, the appropriate size socket spanner head piece is placed on the nut and the adapter 19 in serted into the head piece. The appropriate end of the hollow impact shaft is then engaged with the free end 18 of the adapter and the reduced end of the stabilizing bar inserted into the opposite end of the impact shaft.

The device thus being assembled, pressure is applied along the stabilizing bar to retain the socket spanner head piece 34 in engagement with the nut While the operator swings the handle back through any portion of 90 and then drives it forward so as to bring the pawl 30 into sharp impacting engagement with a shoulder 28 on one peding the removal of the nut.

towards the shoulder 28 with which the pawl comes into contact so that a full face-to-face engagement between the pawl and the shoulder is obtained. After delivering the impact, the handle is merely returned to its original position and again swung forward until the pawl engages the shoulder thereby applying a further jarring-impact tendis one of the reasons for the surprising effectiveness of the present device as compared with known types. of ratchet wrenches or the like.

When a nut has remained for a lorigtime on a bolt,

crystal growths cementing the nut to the bolt commonly arise and these are often more resistant to normal leverage as applied by known ratchet wrenches or the like than the bolt itself so that the application of leverage in known manner often results in shearingof the bolt. n the other hand; it has been found that the application of shocks or jarring impacts to the nut by means of the pres ent device is surprisingly effective in shattering the afore said crystal adhesions with the result that shearing ofthe bolt does not normally occur. Also, it may readily be appreciated that the pawl and camlike projections of the present device are adapted to transmit; shocks or jarringimpacts whereas the corresponding parts in a normal ratchet wrench are not so adapted and are only suitable for the transmission of a steady-leverage.

After having loosened the nut by theapplication of the requisitenumber of impactsin the manner described, the handle can be pulledback through an angle suflicient to cause the spring-loaded pawl to ride over the edge of the sloping surface 29. with which it happenss to be in contact and to drop into engagement with the next shoulder 28, thereby permitting the tool to be used thereafter if desired somewhat in the same manner as a known type of ratchet wrench. Should further tight sections be encountered however, the shock or impact method of operation may be reintroduced until complete removal is effected. I

If it is necessary touse the device in a restricted space, the normal handle may be removed and replaced by a shorter handle. On the other hand, if a longer handle is desired, such may be fitted in place of the normal handle or the cushioned hand grip 27 may be removed in order to allow the insertion of an extra handle into the interior of the normal handle so as to increase the efiective handle length. Alternatively the extra handle may be fitted exteriorly over the existing handle. Also, adjustment of the position of the working arc of the handle may be achieved readily merely by rotating the headpiece 34 to the appropriate positionbefore engaging it with the nut.-

From the above description, it will be obvious that the tool can be used for the loosening or tightening of nuts, studs, bolts or the like having either left or right handed threads by turning the housing in the appropriate direction before engagingthe impact shaft with the adapter, bearing in mind the orientation of the shoulders 0n the projections onthe impact shaft and the direction in Whichthe nut or the like is to'be turned.

In the device described above, the impact shaft is provided with four-cam-like projections, but it is obvious that this number may be varied according to circumstances. For instance the number'of projections may be reduced to three, while in some cases it may be convenient to increase the number to say. six. Of course the greater the number of projections present, the less is the free angle of movement of the handle and. for normal usage, fourprojections providing a free angle of movement of 90 are, preferred.

In the modification illustrated in Figure 5, the impact shaft, instead of being hollowed at its ends as in Figures. 1 to 4, is provided with square or hexagonal studs 35 which project from its ends and areadapted toengage with expanded hollow ends 36, 37 of an adapter and stabilizing shaft respectively. This construction has. the advantagethat it avoids the provision of intermediate non-.

circular portions as at 13-, 14 of the hollowed" end sections:

'4. of the impact shaft described in relation to Figures 1 to 4.

This invention thus provides a device which permits the removal of nuts, studs or bolts that would be difficult or impossible to remove by ordinary means, and moreover, the removal is effected without damage such as occurs with the use of oxy-acetylene torches, hammers, chisels and the like. The force applied-is completely at the controlof the operator and complete removal can be effected without re-p'ositioning' the tool. The device is readily portable and requires no electric, pneumatic or hydraulic sources of power and retains its efficiency in use as there are no springs or similar parts liable to fatigue.

I claim:

1. A shock wrench comprising a housing, an impact shaft rotatably mounted within said housing, an impact receiving member rigidly secured to said shaft, said impact receiving member comprising a series of steeply sloping. abutment faces directed transversely of the axis of'said shafteach-of which isconnected to an adjoining race by a gently r'isingsurface extending from the base ofone face to the top of the adjoining face, an impact transmitting member mounted in said housing, spring meansadapted to-urge said impact transmitting member ina direction towardszsaid impact receiving member, the impact transmititng member being provided with a face ada'ptedtoengage oneof the said steeply sloping abutment" faces= on rotation of the said housing in one direction' relatively to said shaft, the impact transmitting member beingshaped to provide only an edge contact with said gently rising surfaces under the influence of said spring means-to ensure afull face-to-face engagement between the said face of the impact transmitting. member and 'or'le of the said steeply sloping abutment faces on rotation of said housing relatively to said shaft, means connecting said shaft non-rotatably with a nut, stud or bolt and an elongated handle secured" to said housing, whereby a sudden shock loading tending to rotate said nut, and or bolt may be delivered through said shaft by the 'engagem'ent of theimpact transmitting member with one of; the steeply sloping-impact faces of said impact receiving member, the saidimpact transmitting member and: the said impact receiving member being adapted to transmit a sudden shock loading to the nut, stud or bolt after a free swinging movement of the handle and the saidi gently risingsurfaces; on the impact receiving memberjbe'ingr such asto allow the impact receiving member and: the impact transmitting member to rotate relatively to each other, whereby the impact transmitting member can'pass over one of the said gently rising surfaces from aposition atthe base of onelof the steeply sloping abutment faces tothe base of an adjoining steeply sloping abutment face.

2.-A shock Wench comprising a housing, an impact shaft rotatably mounted within said housing, an impact receiving member. rigidly secured to said shaft, a series of steeply sloping abutment faces on the impact receiving member and directedztransverselyof the axis of said shaft,

1 each of thesteeply sloping abutment faces on the impact receiving member being connected to an adjoining abutment face. by a gently rising surface extending from the base ofone abutment face to the top of the adjoining face, an impact transmitting member mounted in said housing, spring means normally maintaining said impact transmitting member in contact with one of the said gently impact receiving member, the said gently rising surfaces of the impact receiving member being such as to allow the impact receiving member and the impact transmitting member to rotate relatively to each other, whereby the impact transmitting member can pass over one of the said gently rising surfaces from a position at the base of one of the steeply sloping abutment faces to the base of an adjoining steeply sloping face.

3. A shock wrench as claimed in claim 2, and further comprising a stabilizing bar connected to the impact shaft, whereby pressure may be directed along the axis of said impact shaft to maintain the device in engagement during use with the nut, stud or bolt.

4. A shock wrench as claimed in claim 2, in which the impact shaft is hollow at least at one end and the means connecting the impact shaft with a nut, stud or bolt comprises a socket spanner adapter adapted to fit non-rotatably into the said hollow end of the impact shaft and a socket spanner head piece adapted to be non-rotatably connected to the adapter.

5. A shock wrench as claimed in claim 2, in which the impact shaft is provided at one end with a projection and the means connecting the impact shaft with a nut, stud or bolt comprises a socket spanner adapter adapted to fit non-rotatably onto the said projection and a socket spanner head piece adapted to be non-rotatably connected to the adapter,

References Cited in the file of this patent UNITED STATES PATENTS 2,086,261 Douglass July 6, 1937 2,112,693 Douglass Mar. 29, 1938 2,256,496 Robinson Sept. 23, 1941 2,342,783 Uron et al Feb. 29, 1944 2,661,647 Swenson Dec. 8, 1953 2,788,689 Potter et al. Apr. 16, 1957 2,793,551 Ford May 28, 1957 FOREIGN PATENTS 878,480 Germany June 5, 1953 

